Critical care nursing clinics of North America
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Crit Care Nurs Clin North Am · Sep 2014
ReviewExploring hemodynamics: a review of current and emerging noninvasive monitoring techniques.
The lack of randomized controlled trials suggesting improved outcomes with pulmonary artery catheter use and pressure-based hemodynamic monitoring has led to a decrease in pulmonary artery catheter use. However, an increasing amount of literature supporting stroke volume optimization (SVO) has caused a paradigm shift from pressure-based to flow-based techniques. This article discusses emerging flow-based techniques, supporting evidence, and considerations for use in critical care for methods such as Doppler, pulse contour, bioimpedance, bioreactance, and exhaled carbon dioxide. Regardless of the device chosen, the SVO algorithm approach should be considered, and volume challenges should be guided by dynamic assessments of fluid responsiveness.
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The cardiovascular system (macrocirculation) circulates blood throughout the body, but the microcirculation is responsible for modifying tissue perfusion and adapting it to metabolic demand. Hemodynamic assessment and monitoring of the critically ill patient is typically focused on global measures of oxygen transport and utilization, which do not evaluate the status of the microcirculation. Despite achievement and maintenance of global hemodynamic and oxygenation goals, patients may develop microcirculatory dysfunction with associated organ failure. A thorough understanding of the microcirculatory system under physiologic conditions will assist the clinician in early recognition of microcirculatory dysfunction in impending and actual disease states.
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The purpose of this article is to propose optimal weaning of vasopressors in patients with septic shock. Topics discussed include pathophysiology of sepsis and septic shock, treatment guidelines for sepsis, autoregulation of blood flow, vasopressors used in septic shock, weaning recommendations, monitor alarms in the intensive care unit, and new directions in sepsis research.
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Functional components of the microcirculation provide oxygen and nutrients and remove waste products from the tissue beds of the body's organs. Shock states overwhelmingly stress functional capacity of the microcirculation, resulting in microcirculatory failure. ⋯ In nonseptic shock states, the microcirculation is better able to compensate for alterations in vascular resistance, cardiac output, and blood pressure. Therefore, global hemodynamic and oxygen delivery parameters are appropriate for assessing, monitoring, and guiding therapy in hypovolemic and cardiogenic shock but, alone, are inadequate for septic shock.
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Crit Care Nurs Clin North Am · Sep 2014
ReviewMonitoring tissue blood flow and oxygenation: a brief review of emerging techniques.
This article describes promising emerging technologies developed for measuring tissue-level oxygenation or perfusion, each with its own inherent limitations. The end user must understand what the instrument measures and how to interpret the readings. ⋯ Assessment of the metabolic state of the extracellular space with existing technology and proxy indicators of metabolic status are discussed. Also addressed are potential sources of variation for each technique, and the role that the clinician plays in the proper interpretation of the data.